Percentage Change Calculator
Calculate the percentage increase or decrease between two values using (new − old) ÷ |old| × 100.
How it works
- 1Enter the original (old) value and the new value into the two fields.
- 2The calculator applies (new − old) ÷ |old| × 100 and returns a signed percentage — positive for an increase, negative for a decrease.
- 3The detail line shows the absolute difference and tells you whether the change is an increase or a decrease.
Use cases
- Track price changes — e.g. a product that rose from $80 to $100 changed by +25%.
- Measure growth metrics such as monthly active users or revenue quarter-over-quarter.
- Compare exam scores, weights, or any before-and-after measurement to quantify improvement or decline.
Frequently asked questions
What’s the difference between percentage change and percentage points?
Percentage change measures the relative shift from the original value (50% → 75% is a +50% change), while a percentage-point difference is the arithmetic gap (75 − 50 = 25 pp). This calculator gives the relative percentage change.
What happens when the original value is 0?
Division by zero makes percentage change undefined. The calculator shows — in that case and explains why in the detail line.
How do I tell increase from decrease?
The sign tells you everything: a positive percentage means the new value is higher than the original (increase); a negative percentage means it is lower (decrease).
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